491147 - Smooth scrolling perfect scroll-up; jitters scroll-down

Status: RESOLVED WORKSFORME

(Core :: General, defect)

Description

[Mark Richards]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1b4) Gecko/20090423 Firefox/3.5b4
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1b4) Gecko/20090423 Firefox/3.5b4

Smooth scrolling works well on http://www.nytimes.com/ but on http://www.boston.com there is a significant difference between scrolling up versus down.

Using up/down arrows, mouse wheel, or scroll bar, scrolling the page down shows visually-perceptive delay in re-painting viewport.  The result is a jitter, not smooth.

Clearly this is content-based, but as the content between these two sites is very complex, it's best left to the experts to figure it out.

Reproducible: Always

Steps to Reproduce:
1.www.boston.com: scroll up and down
2.www.nytimes.com: do the same
3.
Actual Results:  
On boston.com, jitter on scroll down 


Expected Results:  
Smooth scrolling expected in both directions.

Comment 1

[Ernst de Haan]

Works fine for me on Mac OS X 10.5.6 (nl_NL)/Firefox 3.5b4 (nl_NL) on www.boston.com. Tested with scroll wheel only. No jitter whatsoever. Hardware is late 2006 MacBook Pro, with an external screen 1680x1050.

Comment 2

[Mark Richards]

And, the original reporter can't reproduce it either!

I recall having many tabs opened, so thinking perhaps memory depletion?  Attempting to reproduce and it won't.

Comment 3

[Mark Richards]

It showed up again.  This time not on the index page of boston.com but on a story page that I opened.

The page was only about 30KB in size, but rather lengthy as there were many story comments.

I had 6 other tabs opened at the time.  All of these pages were small - most are management interfaces for some server processes - and only one of these auto-refreshes every 60 seconds.

I checked Firefox memory usage - it had been operating all day - and it was around 180KB !!  This is extraordinary.  In 3.0x firefox won't last all day - memory creeps up to almost 1GB and then we finally crash.  So this is the good news.  

Once I closed all the other tabs (testing one at a time) the jitter was gone.  Memory use dropped by only 10K.

So there may be a performance issue related to painting a page with a significant length (but not byte size) when multiple tabs are opened.  What may also be involved are extensions, although none of these do any user interface mods that I know of, other than all in one sidebar, and the mod is expected.

Comment 4

[Robert kinkead]

I have the problem with 3.6b1 jitters both up and down.

Comment 5

[Robert kinkead]

Here are the sites that I am having the problem with;
http://astrafamily.com/index.php, http://www.arizonamoon.eu/, http://boincstats.com/stats/boinc_team_graph.php?pr=bo&teamcpid=a46d60ce3cf44cf6661f00549568627d

It seems to have something to do with sites that have a lot of graphics on them.

Comment 6

[Marco Castelluccio [:marco]]

I can't reproduce with Firefox 10. Could someone test the URLs in comment 5 and comment 1, so that we can close this as WORKSFORME?

Comment 7

[Robert kinkead]

I have not had the problem since I upgraded to my current version 8.0.1

Comment 8

[Ernst de Haan]

Cannot reproduce with Firefox 9.0 Beta on Mac OS X 10.7.2. Also with the sites in comment #5.

PS. I wonder if the steps to reproduce should not include setting smooth scrolling on in the Firefox preferences?

Comment 9

[Marco Castelluccio [:marco]]

I've tried with and without smooth scrolling. However the reporter said the problem was with smooth scrolling.
Ernst and Robert could you try without smooth scrolling?
Robert did you try also with the sites in comment #5?